Extendible and reinforceable nacelle and method for making same

ABSTRACT

A nacelle for a wind turbine includes a cover defining an internal volume. The cover extends along a longitudinal direction, and the cover has a predefined length, a predefined width and a predefined height. The cover has multiple sections configured to be fastened together to form the cover. The multiple sections are configured to fasten to one or more longitudinal extension sections. The longitudinal extension sections are configured to fasten to the cover and extend a longitudinal length of the cover to a second length. The second length is greater than the predefined length.

BACKGROUND OF THE INVENTION

The invention described herein relates generally to wind turbines. More specifically, the invention relates to a nacelle having an extendible length, optionally reinforced structure and a method for making the extendible and reinforceable nacelle.

Wind power is considered one of the cleanest and most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one more rotor blades. The rotor blades capture kinetic energy from wind using known foil principles, and transmit the kinetic energy through rotational energy to turn a shaft that is coupled to the gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be supplied to a utility grid.

Modern wind turbines can be quite large, with many designs having a rotor hub height exceeding 100 meters. In this regard, the logistical costs associated with transporting the wind turbine components to the erection site can be quite substantial and must be factored into the overall cost efficiency of wind energy. In this regard, it has been estimated that rail transportation of wind turbine components can provide approximately a fifty percent savings as compared to other means. However, there are size restrictions on the components that can be transported by rail. For example, generally a width restriction of 4 meters and a height restriction of 5 meters is imposed on components transported by rail and, in this regard, the width and height of the nacelle is becoming a limiting factor for rail transport of the component, particularly as wind turbine designs grow increasingly larger.

In the wind industry today, the nacelle geometries vary with the type of turbine, and are not inter-changeable. Nacelles are custom-designed to the type of turbine configuration. As one example only, a 1.5 MW wind turbine may have a nacelle length of about 9 meters and a 2.5 MW turbine may have a length of about 11 meters. This difference in length is attributable to the larger gearbox and generator used in the 2.5 MW wind turbine. Manufacturing nacelles with different dimensions adds costs in tooling, engineering design, manufacturing, logistics, etc. In addition to this, currently, the nacelles are designed for worst case extreme site wind conditions. The walls and structures are made thicker to enable them to withstand snow and wind loads.

BRIEF DESCRIPTION OF THE INVENTION

In an aspect of the present invention, a nacelle for a wind turbine includes a cover defining an internal volume. The cover extends along a longitudinal direction, and the cover has a predefined length, a predefined width and a predefined height. The cover has multiple sections configured to be fastened together to form the cover. The multiple sections are configured to fasten to one or more longitudinal extension sections. The longitudinal extension sections are configured to fasten to the cover and extend a longitudinal length of the cover to a second length. The second length is greater than the predefined length.

In another aspect of the present invention, a nacelle for a wind turbine includes a cover defining an internal volume. The cover extends along a longitudinal direction and has a predefined length, a predefined width and a predefined height. The cover has multiple sections configured to be fastened together to form the cover. One or more longitudinal extension sections are configured to be fastened to the cover. The longitudinal extension sections are configured to extend a longitudinal length of the cover to a second length, where the second length is greater than the predefined length. The cover maintains the predefined width and the predefined height, where the predefined width and the predefined height are equal to or less than a predefined maximum dimension for truck or rail transport.

In yet another aspect of the present invention, a method for extending a nacelle, where the nacelle has a predefined length, includes the steps of dividing the nacelle at a specified location into a first nacelle segment and a second nacelle segment, and coupling one or more longitudinal extension sections to at least one of the first nacelle segment and the second nacelle segment. The nacelle is lengthened to a second length, where the second length is greater than the predefined length. The dividing step may also include the step of dividing the nacelle at a middle portion or a rear portion of the nacelle. The coupling step may also include coupling the one or more longitudinal extension sections to at least one of the first nacelle segment and the second nacelle segment, or the second nacelle segment.

The method may also include the step of adding a plurality of reinforcement inserts to the nacelle, where the plurality of reinforcement inserts are mounted inside a nacelle wall. The adding step may include adding a plurality of reinforcement braces to the nacelle, and coupling the plurality of reinforcement braces to the plurality of reinforcement inserts. The plurality of reinforcement braces and the plurality of reinforcement inserts are configured to increase structural rigidity and increase strength of the nacelle. The reinforcement braces may have a generally U-shaped, generally V-shaped, generally I-shaped or generally Z-shaped cross-sectional shape. The adding step may include coupling one or more reinforcement panels to the reinforcement braces, where the one or more reinforcement panels are configured to increase a shear strength of the nacelle wall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of an exemplary wind turbine;

FIG. 2 illustrates a partially cut-away perspective view of a portion of the wind turbine of FIG. 1;

FIG. 3 illustrates a schematic view of a nacelle that can be configured to have multiple lengths, according to an aspect of the present invention;

FIG. 4 illustrates a schematic view of a nacelle that can be configured to have multiple lengths, according to an aspect of the present invention;

FIG. 5 illustrates a schematic view of a nacelle that can be configured to have multiple lengths, according to an aspect of the present invention;

FIG. 6 illustrates a cross-sectional view of one known nacelle wall;

FIG. 7 illustrates a cross-sectional view of a laminated nacelle wall having multiple layers, according to an aspect of the present invention;

FIG. 8 illustrates a cross-sectional view of a nacelle wall having a reinforcement brace attached to increase structural rigidity and strength, according to an aspect of the present invention;

FIG. 9 illustrates a cross-sectional view of a reinforcement brace that is generally U-shaped, according to an aspect of the present invention;

FIG. 10 illustrates a cross-sectional view of a generally V-shaped reinforcement brace, according to an aspect of the present invention;

FIG. 11 illustrates a cross-sectional view of a reinforcement brace that is generally I-shaped, according to an aspect of the present invention;

FIG. 12 illustrates a cross-sectional view of a generally Z-shaped reinforcement brace, according to an aspect of the present invention;

FIG. 13 illustrates a cross-sectional view of a reinforcement brace that is generally V-shaped with supplemental mounting legs, according to an aspect of the present invention;

FIG. 14 illustrates a cross-sectional view of a partial wall of a nacelle reinforced by a combination of reinforcing braces and reinforcing panels, according to an aspect of the present invention; and

FIG. 15 illustrates a flowchart for a method for extending a nacelle, according to an aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific aspects/embodiments of the present invention will be described below. In an effort to provide a concise description of these aspects/embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with machine-related, system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present invention, the articles “a”, “an”, and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. Additionally, it should be understood that references to “one embodiment”, “one aspect” or “an embodiment” or “an aspect” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments or aspects that also incorporate the recited features.

FIG. 1 is a perspective view of an exemplary wind turbine 10. Wind turbine 10 described and illustrated herein is a wind generator for generating electrical power from wind energy. In some known wind turbines, wind turbine 10 is any type of wind turbine, such as, but not limited to, a windmill (not shown). Moreover, wind turbine 10 includes a horizontal-axis configuration. In some known wind turbines, wind turbine 10 includes a vertical-axis configuration (not shown). Wind turbine 10 may be coupled to an electrical load (not shown), such as, but not limited to, a power grid (not shown), and may receive electrical power therefrom to drive operation of wind turbine 10 and/or its associated components and/or may supply electrical power generated by wind turbine 10.

Wind turbine 10 includes a nacelle 12, and a rotor (generally designated by 14) coupled to body 12 for rotation with respect to body 12 about an axis of rotation 16. In the exemplary embodiment, nacelle 12 is mounted on a tower 18. The height of tower 18 is any suitable height enabling wind turbine 10 to function as described herein. Rotor 14 includes a hub 20 and a plurality of blades 22 (sometimes referred to as “airfoils”) extending radially outwardly from hub 20 for converting wind energy into rotational energy. Although rotor 14 is described and illustrated herein as having three blades 22, rotor 14 may include any number of blades 22.

FIG. 2 is a partially cut-away perspective view of a portion of the wind turbine 10. Wind turbine 10 includes an electrical generator 26 coupled to rotor 14 for generating electrical power from the rotational energy generated by rotor 14. Generator 26 is any suitable type of electrical generator, such as, but not limited to, a wound rotor induction or permanent magnet generator. Rotor 14 includes a low speed rotor shaft 28 coupled to rotor hub 20 for rotation therewith. Generator 26 is coupled to a high speed rotor shaft 30 such that rotation of rotor shaft 28 drives rotation of the generator rotor, and therefore operation of generator 26. In the exemplary embodiment, high speed rotor shaft 30 is coupled to low speed shaft 28 through a gearbox 32, although in other embodiments generator rotor shaft 30 is coupled directly to rotor shaft 28. The rotation of rotor 14 drives the generator rotor to thereby generate variable frequency AC electrical power from rotation of rotor 14.

In some embodiments, wind turbine 10 includes a brake system (not shown) for braking rotation of rotor 14. Furthermore, in some embodiments, wind turbine 10 includes a yaw system 40 for rotating nacelle 12 about an axis of rotation 42 to change a yaw of rotor 14. Yaw system 40 is coupled to and controlled by a control system(s) 44. In some embodiments, wind turbine 10 includes anemometry 46 for measuring wind speed and/or wind direction. Anemometry 46 is coupled to control system(s) 44 for sending measurements to control system(s) 44 for processing thereof. In the exemplary embodiment, control system(s) 44 is mounted within nacelle 12. Alternatively, one or more control systems 44 may be remote from nacelle 12 and/or other components of wind turbine 10. Control system(s) 44 may be used for, but is not limited to, overall system monitoring and control including, for example, pitch and speed regulation, high-speed shaft and yaw brake application, yaw and pump motor application, and/or fault monitoring. Alternative distributed or centralized control architectures may be used in some embodiments.

FIG. 3 illustrates a schematic view of a nacelle 300 that can be configured to have multiple lengths, according to an aspect of the present invention. The nacelle 300 is comprised of a cover defining an internal volume. The cover (or nacelle) extends along a longitudinal direction 301, and the cover has a predefined length (L₁+L₂), a predefined width (W₁) and a predefined height (H₁). The cover has multiple sections and the multiple sections are configured to be fastened together to form the cover (or nacelle). The multiple sections may include the front nacelle sections 310, 312, the rearward nacelle sections 314, 316, the rear panel sections 318, 320, and the roof section 322. The front sections 310, 312 are typically bolted together along flange 330. The rearward sections 314, 316 are also typically bolted together along a similar flange (not shown). The front section 310 is also bolted to rearward section 314 along flanged joint 331, and the front section 312 is similarly connected to rearward panel 316. In some configurations, the rear panels 318 and 320 may be bolted to each other and to the rearward panels 314, 316 along similar flanged joints. In this configuration the nacelle would have a predefined (or first) length of L₁+L₂.

The roof section 322 may also be bolted to the adjoining sections. The roof section 322 may also include one or more railings 323, a roof hatch 324, a meterological mounting pad 325 and an aviation light mounting pad 326. The sections have been described as being bolted together, but this is only one method, and it is to be understood that the sections may be fastened together by any suitable fastening means, including but not limited to, mechanical fasteners, adhesives, clamps, or combinations thereof

The multiple sections are also configured to fasten to one or more longitudinal extension sections 341, 342, 343. For example, the longitudinal extension sections 341 and 342 would be rearward sections and the longitudinal extension section 343 would be a roof section. The roof section 343 may also include a meterological mounting pad 345 and an aviation light mounting pad 346. The longitudinal extension sections 341, 342 and 343 are configured to fasten to the cover and extend a longitudinal length of the cover to a second length (L₁+L₂+L₃). As will be evident, the second length (L₁+L₂+L₃) is greater than the predefined length (L₁+L₂). In this example, the longitudinal extension sections 341, 342 and 343 are configured to be fastened to a rear portion of the cover (or nacelle). As one example only, the predefined length might be about 9 meters to about 11 meters, and the second length might be about 10 meters to about 13 meters. These ranges are only examples, and it is to be understood that any suitable nacelle length may be used as desired with the specific wind turbine. Only the length may be varied for different configurations to accommodate component size variations. The width and height of the nacelle will remain the same in both the “short” or “long” configurations (i.e., without or including the longitudinal extension sections, respectively). As examples only, the width W₁ may be about 4 meters, and the height H₁ may be about 4 meters. However, the widths and heights for specific wind turbines may not be equal, and/or may vary from this range as desired in the specific application. Furthermore, the width W₁ and height H₁ may be designed for max-case, be standard for all configurations and would comply with global road and rail transportation limits. For example, the width W₁ and the height H₁ may be equal to or less than a pre-defined maximum dimension for truck or rail transport.

FIG. 4 illustrates a schematic view of a nacelle 400 that can be configured to have multiple lengths, according to an aspect of the present invention. The nacelle 400 is comprised of a cover defining an internal volume. The cover (or nacelle) extends along a longitudinal direction, and the cover has a predefined length (L₁+L₂), a predefined width (not shown) and a predefined height (H₁). The cover has multiple sections and the multiple sections are configured to be fastened together to form the cover (or nacelle). The multiple sections may include the front sections 410, the rearward sections 414, the rear panel sections 418, and the roof section 422. The sections may be bolted together along flanges or other mounting means. In a “short” configuration the nacelle would have a predefined length of L₁+L₂, as longitudinal extension sections 441, 443 would be omitted.

However, the nacelle 400 can be assembled in a “long” configuration by fastening one or more longitudinal extension sections 441, 443 to the front section 410, rearward section 414 and/or the roof section 422 and rear section 418. For example, the longitudinal extension section 441 would be fastened to a middle portion of the cover, or to the front section 410 and rearward section 414. The longitudinal extension roof section 443 could be fastened to roof section 422 and rear section 418. The roof section 443 may also include a meterological mounting pad (not shown) and/or an aviation light mounting pad (not shown). The longitudinal extension sections 441 and 443 are configured to fasten to the cover and extend a longitudinal length of the cover to a second length (L₁+L₂+L₃). As will be evident, the second length (L₁+L₂+L₃) is greater than the predefined length (L₁+L₂). As one example only, the predefined length might be about 9 meters to about 11 meters, and the second length might be about 10 meters to about 13 meters. The longitudinal extension sections may have a length of about 1 meter to 3 meters, and multiple longitudinal extension sections could be connected together to further increase the overall length of the nacelle 400. These ranges are only examples, and it is to be understood that any suitable nacelle length may be used as desired with the specific wind turbine. The width and height of the nacelle will remain substantially the same in both the “short” or “long” configurations.

FIG. 5 illustrates a schematic view of a nacelle 500 that can be configured to have multiple lengths where the longitudinal extension section 518 forms the rear portion of the cover, according to an aspect of the present invention. The nacelle 500 is comprised of a cover defining an internal volume. The cover (or nacelle) extends along a longitudinal direction, and the cover has a predefined length (L₁+L₂), a predefined width (not shown) and a predefined height (H₁). The cover has multiple sections and the multiple sections are configured to be fastened together to form the cover (or nacelle). The multiple sections may include the front sections 510, the rearward sections 514, the rear panel sections/longitudinal extension sections 518, and the roof section 522. The sections may be bolted together along flanges or other mounting means. In a “short” configuration the nacelle would have a predefined length of L₁+L₂, as a shorter rear panel section (not shown, but similar to rear panel section 418 in FIG. 4) would be used. The nacelle 500 can be assembled in a “long” configuration by fastening a longer rear panel longitudinal extension section 518 to the rearward section 514 and roof section 522. The rear panel longitudinal extension section 518 is configured to fasten to the cover and extend a longitudinal length of the cover to a second length (L₁+L₂+L₃). As will be evident, the second length (L₁+L₂+L₃) is greater than the predefined length (L₁+L₂). As one example only, the predefined length might be about 9 meters to about 11 meters, and the second length might be about 10 meters to about 13 meters. The rear panel longitudinal extension section 518 may have a length of about 1 meter to about 3 meters or more. These ranges are only examples, and it is to be understood that any suitable rear panel longitudinal extension section length may be used as desired with the specific wind turbine. The width and height of the nacelle will remain substantially the same in both the “short” or “long” configurations.

FIG. 6 illustrates a cross-sectional view of one known nacelle wall. The nacelle (or cover) wall 600 is typically comprised of a core 620 sandwiched between two outer layers 610. The core 620 might be formed of a polyurethane foam or a poly-vinyl chloride foam, and the core adds structural support to the wall 600. The outer layers 610 might be formed of a glass reinforced plastic (e.g., fiberglass) or a fiber reinforced plastic, and the outer layers 610 are bonded to the core 620. Optionally, the nacelle may include stiffening ribs that are formed of outer wall 612 and core 622. The outer wall 612 and core 622 are similar to outer layer 610 and core 620, respectively. Current nacelles are designed for worst-case static load conditions (snow load), and have thicker/heavier structures, making them very heavy. Tooling required to make these nacelles are different and expensive. Current nacelles are shipped across the globe via trucks, rail or ships. Since these nacelles are heavy and occupy huge volumes, transportation and costs are the major issues. In some cases, only one of these various nacelles fit in a shipping container during ocean transport. For road transport, only one (or a portion) of these nacelles may be shipped at a time on a truck, and special permits are needed for oversize loads. In addition, flag cars are required for warning and protecting other roadway users. The nacelle wall structure shown in FIG. 6 does not lend itself to lightweight or customized construction.

FIG. 7 illustrates a cross-sectional view of a laminated nacelle wall 700 having multiple layers, according to an aspect of the present invention. The nacelle (or cover) wall 700 is comprised of a core 720 sandwiched between two outer layers 710. The core 720 may be formed of a polyurethane foam, a poly-vinyl chloride (PVC) foam, polyethylene terephthalate (PET), polyisocyanurate (PIR) or any other suitable material. The outer layers 710 may be formed of a glass reinforced plastic (e.g., fiberglass), a fiber reinforced plastic or any other suitable material. The outer layers 710 are bonded to the core 720, and both the outer walls 710 and core 720 add structural support to the wall 700. Optionally, the nacelle may include stiffening ribs that are formed of outer wall 712 and core 722. The outer wall 712 and core 722 are similar in material to outer layer 710 and core 720, respectively.

Reinforcement inserts 730 are mounted inside the laminated wall 700 at various locations. The reinforcement inserts 730 may be formed of steel, steel alloys or any other suitable high-strength material. The inserts 730 are configured for attachment to reinforcement braces 840, and the braces are configured to increase the structural rigidity and strength of the wall 700 (and nacelle/cover). The reinforcement inserts 730 may be mounted inside the stiffening ribs 712, 722 by mechanical fasteners, adhesive or any other suitable attachment means. Alternatively, or in addition, the reinforcement inserts 730 may be mounted inside the wall defined by outer layer 710 and core 720. The reinforcement inserts 730 may include threaded holes (not shown) that are preconfigured for fasteners (e.g., screws or bolts), and these fasteners are used when fastening reinforcement braces 840 to the inserts 730.

FIG. 8 illustrates a cross-sectional view of a nacelle wall 700 having a reinforcement brace attached, to increase structural rigidity and strength, according to an aspect of the present invention. A reinforcement brace 840 is fastened to the reinforcement inserts 730 by a plurality of fasteners 842. For example, am internally threaded hole in reinforcement insert 730 may engage external threads on fastener 842. The fasteners 842 may be screws, bolts, rivets or any other suitable mechanical fastener. Alternatively, or in addition to the fasteners 842, the braces 840 may be attached to wall 712 by the means of adhesive. The reinforcement brace 840 may be comprised of steel, steel alloys, aluminum or any other suitable material. Multiple reinforcement braces 840 may be used on the sides and/or top of the nacelle, and these braces would preferably be installed on the inner walls of the nacelle. However, the braces 840 could also be installed on the outer wall if desired. The reinforcement brace 840 depicted in FIG. 8 may be viewed as having a generally U-shaped or V-shaped form, and it is to be understood that the braces 840 could also be I-shaped or Z-shaped.

FIG. 9 illustrates a cross-sectional view of a reinforcement brace 900 that is generally U-shaped. The reinforcement brace 900 may be attached to reinforcement inserts 930 by fasteners 932. The U-shaped reinforcement brace would be useful on rectangular shaped stiffening ribs. In FIGS. 9-12 the nacelle wall has been omitted for clarity. FIG. 10 illustrates a cross-sectional view of a reinforcement brace 1000 that is generally V-shaped. The reinforcement brace 1000 may be attached to reinforcement inserts 1030 by fasteners 1032. The V-shaped reinforcement brace would be useful on trapezoidal shaped stiffening ribs. FIG. 11 illustrates a cross-sectional view of a reinforcement brace 1100 that is generally I-shaped. The reinforcement brace 1100 may be attached to reinforcement inserts 1130 by fasteners 1132. The I-shaped reinforcement brace would be useful on straight or flat nacelle walls. FIG. 12 illustrates a cross-sectional view of a reinforcement brace 1200 that is generally Z-shaped. The reinforcement brace 1200 may be attached to reinforcement inserts 1230 or reinforcement panels by fasteners 1232. The Z-shaped reinforcement brace would be useful when adding a reinforcement panel to the Z-shaped reinforcement brace 1200. FIG. 13 illustrates a cross-sectional view of a reinforcement brace 1300 that is generally V-shaped with supplemental mounting legs. The reinforcement brace 1300 may be attached to reinforcement inserts 1330 or reinforcement panels by fasteners 1332. The V-shaped reinforcement brace with supplemental mounting legs would be useful when attaching the brace 1300 to multiple reinforcement inserts, trapezoidal stiffening ribs (or trapezoidal nacelle wall sections), or to flat nacelle walls. In addition, the reinforcement braces may be easily assembled in the field, if needed.

FIG. 14 illustrates a cross-sectional view of a partial wall of a nacelle reinforced by a combination of reinforcing braces 1440 and reinforcing panels 1450, according to an aspect of the present invention. The nacelle wall includes outer walls 1410 and core 1420. Reinforcement inserts 1430 can be mounted inside the nacelle wall. A plurality of generally Z-shaped reinforcement braces 1440 are attached to the nacelle wall by the use of fasteners 1442 and reinforcement inserts 1430. Alternatively, the fastener 1442 and insert 1430 may be replaced by a rivet or expanding plug 1446 and fastener 1445. The reinforcement panel 1450 is fastened to the braces 1440 by a nut 1444 and bolt 1442 system. However, all the fasteners could be replaced by any suitable mechanical or adhesive fastening system. The reinforcement panel 1450 may be formed of fiber reinforced plastic, glass reinforced plastic, metal or any other suitable material. The reinforcement panel 1450 is configured to increase the shear strength of the laminated wall of the nacelle. The panels 1450 may be installed on the walls and/or roof of the nacelle, and preferably on the interior surfaces of the nacelle (mainly for ease of access and aesthetic reasons). Alternatively, brace 1440 may be replaced by any of braces 900, 1000, 1100, 1200 or 1300 (or any other desired shape of brace) when used between wall 1410 and panel 1450. It is also to be understood that the reinforcement braces and panels may be located in or on the nacelle walls/roof, and/or the longitudinal extension section walls/roof.

FIG. 15 illustrates a flowchart for a method for extending a nacelle, according to an aspect of the present invention. The method 1500 for extending a nacelle 300, where the nacelle 300 has a predefined (or first) length (L₁+L₂), includes a step 1510 of dividing the nacelle 300 at a specified location into a first nacelle segment (e.g., 314, 316) and a second nacelle segment (e.g., 318, 320), and a coupling step 1520 that couples one or more longitudinal extension sections 341, 342, 343 to at least one of the first nacelle segment and the second nacelle segment. The nacelle 300 is lengthened to a second length (L₁+L₂+L₃), where the second length (L₁+L₂+L₃) is greater than the predefined length (L₁+L₂). The dividing step 1510 may also include the step of dividing the nacelle at a middle portion or a rear portion of the nacelle. The coupling step 1520 may also include coupling the one or more longitudinal extension sections to at least one of the first nacelle segment and the second nacelle segment, or the second nacelle segment.

The method may also include the step 1530 of adding a plurality of reinforcement inserts 730, 930, 1030, 1130, 1230, 1330 to the nacelle, where the plurality of reinforcement inserts are mounted inside a nacelle wall. The method 1500 may include adding a plurality of reinforcement braces 840, 900, 1000, 1100, 1200, 1300 to the nacelle, and coupling the plurality of reinforcement braces 840, 900, 1000, 1100, 1200, 1300 to the plurality of reinforcement inserts 730, 930, 1030, 1130, 1230, 1330. The plurality of reinforcement braces 840, 900, 1000, 1100, 1200, 1300 and the plurality of reinforcement inserts 730, 930, 1030, 1130, 1230, 1330 are configured to increase structural rigidity and increase strength of the nacelle. The reinforcement braces 840, 900, 1000, 1100, 1200, 1300 may have a generally U-shaped, generally V-shaped, generally I-shaped or generally Z-shaped cross-sectional shape. The method 1500 may include coupling one or more reinforcement panels 1450 to the reinforcement braces 840, 900, 1000, 1100, 1200, 1300, where the one or more reinforcement panels 1450 are configured to increase a shear strength of the nacelle wall.

A concept being proposed here is to make a universal nacelle design that can be extended as needed. The nacelle width and height will be constant for all configurations, with variability in length. The length can be varied by adding annular sections (e.g., longitudinal extension sections) to the rear or center. These sections can be bolted-on to the base (i.e., short configuration) nacelle. This provides an expandable design and common part savings. The nacelle will be designed for the max-case width/height, for standard weather IEC load conditions. This will significantly reduce tooling costs since only one design can be used for all applications. For certain applications where more demanding snow or wind load requirements have to be met, features will be provided in the base nacelle structure to add extra panels or steel braces/trusses (e.g., reinforcement braces) to the top and sides to carry the extra loads. These panels or braces can be easily bolted-on to the base structure in the field. Transportation costs are also significantly reduced since the base nacelle is much lighter.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

1. A nacelle for a wind turbine, the nacelle comprising: a cover defining an internal volume, the cover extending along a longitudinal direction, the cover having a predefined length, a predefined width and a predefined height; the cover having multiple sections, the multiple sections configured to be fastened together to form the cover, the multiple sections are configured to fasten to one or more longitudinal extension sections, the one or more longitudinal extension sections are configured to fasten to the cover and extend a longitudinal length of the cover to a second length, the second length being greater than the predefined length.
 2. The nacelle of claim 1, further comprising: the one or more longitudinal extension sections fastened to the cover; and wherein the cover has the second length.
 3. The nacelle of claim 2, wherein the cover maintains the predefined width and the predefined height.
 4. The nacelle of claim 3, wherein the one or more longitudinal extension sections are fastened to at least one of: a middle portion of the cover or a rear portion of the cover.
 5. The nacelle of claim 3, wherein the one or more longitudinal extension sections form a rear portion of the cover.
 6. The nacelle of claim 1, the cover further comprising: a laminated wall having multiple layers; and reinforcement inserts mounted inside the laminated wall, the reinforcement inserts configured for attachment to reinforcement braces.
 7. The nacelle of claim 6, the cover further comprising: the reinforcement braces fastened to the reinforcement inserts; wherein the reinforcement braces and the reinforcement inserts are configured to increase structural rigidity and increase strength of the cover.
 8. The nacelle of claim 7, wherein the reinforcement braces have a cross-sectional shape of at least one of: generally U-shaped, generally V-shaped, generally I-shaped or generally Z-shaped.
 9. The nacelle of claim 8, the nacelle further comprising: one or more reinforcement panels fastened to the reinforcement braces; and wherein the one or more reinforcement panels are configured to increase a shear strength of the laminated wall of the cover.
 10. A nacelle for a wind turbine, the nacelle comprising: a cover defining an internal volume, the cover extending along a longitudinal direction, the cover having a predefined length, a predefined width and a predefined height, the cover having multiple sections, the multiple sections configured to be fastened together to form the cover; one or more longitudinal extension sections configured to be fastened to the cover, the one or more longitudinal extension sections are configured to extend a longitudinal length of the cover to a second length, the second length being greater than the predefined length; and wherein the cover maintains the predefined width and the predefined height, the predefined width and the predefined height being equal to or less than a predefined maximum dimension for truck or rail transport.
 11. The nacelle of claim 10, wherein the one or more longitudinal extension sections are: fastened to a middle portion of the cover or a rear portion of the cover; or form a rear portion of the cover.
 12. The nacelle of claim 11, the cover further comprising: a laminated wall having multiple layers; a plurality of reinforcement inserts mounted inside the laminated wall, the reinforcement inserts configured for attachment to reinforcement braces; the reinforcement braces fastened to the reinforcement inserts; and wherein the reinforcement braces and the reinforcement inserts are configured to increase structural rigidity and increase strength of the cover.
 13. The nacelle of claim 12, the nacelle further comprising: one or more reinforcement panels fastened to the reinforcement braces; and wherein the one or more reinforcement panels are configured to increase a shear strength of the laminated wall of the cover.
 14. A method for extending a nacelle, the nacelle having a predefined length, the method comprising: dividing the nacelle at a specified location into a first nacelle segment and a second nacelle segment; coupling one or more longitudinal extension sections to at least one of the first nacelle segment and the second nacelle segment; and wherein the nacelle is lengthened to a second length, the second length being greater than the predefined length.
 15. The method of claim 14, the dividing step further comprising: dividing the nacelle at a middle portion or a rear portion of the nacelle.
 16. The method of claim 14, the coupling step further comprising coupling the one or more longitudinal extension sections to at least one of: the first nacelle segment and the second nacelle segment, or the second nacelle segment.
 17. The method of claim 14, further comprising: adding a plurality of reinforcement inserts to the nacelle; and wherein the plurality of reinforcement inserts are mounted inside a nacelle wall.
 18. The method of claim 17, further comprising: adding a plurality of reinforcement braces to the nacelle; and coupling the plurality of reinforcement braces to the plurality of reinforcement inserts; and wherein the plurality of reinforcement braces and the plurality of reinforcement inserts are configured to increase structural rigidity and increase strength of the nacelle.
 19. The method of claim 18, wherein the plurality of reinforcement braces have a cross-sectional shape of at least one of: generally U-shaped, generally V-shaped, generally I-shaped or generally Z-shaped.
 20. The method of claim 18, further comprising: coupling one or more reinforcement panels to the reinforcement braces; and wherein the one or more reinforcement panels are configured to increase a shear strength of the nacelle wall. 